Alignment indication for transcutaneous energy transfer

Abstract

System for transcutaneous energy transfer. An implantable medical device, adapted to be implanted in a patient, has componentry for providing a therapeutic output. The implantable medical device has an internal power source and a secondary coil operatively coupled to the internal power source. An external power source, having a primary coil, provides energy to the implantable medical device when the primary coil of the external power source is placed in proximity of the secondary coil of the implantable medical device and thereby generates a current in the internal power source. An alignment indicator reports the alignment as a function of the current generated in the internal power source with a predetermined value associated with an expected alignment between the primary coil and secondary coil.

What is claimed is: 
     
       1. A system for transcutaneous energy transfer, comprising:
 an implantable medical device having componentry for providing a therapeutic output, said implantable medical device having an internal power source and a secondary coil operatively coupled to said internal power source, said implantable medical device adapted to be implanted in a patient; and 
 an external power source having a primary coil, said external power source providing energy to said implantable medical device when said primary coil of said external power source is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current, having a value, passing through said internal power source: 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a measured current associated with said current passing through said internal power source. 
 
     
     
       2. A system for transcutaneous energy transfer, comprising:
 an implantable medical device having componentry for providing a therapeutic output, said implantable medical device having an internal power source and a secondary coil operatively coupled to said internal power source, said implantable medical device adapted to be implanted in a patient; and 
 an external power source having a primary coil, said external power source providing energy to said implantable medical device when said primary coil of said external power source is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current, having a value, passing through said internal power sources; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said current passing through said internal power source declines as said voltage of said internal power source increases during a charging cycle. 
 
     
     
       3. A system for transcutaneous energy transfer, comprising:
 an implantable medical device having componentry for providing a therapeutic output, said implantable medical device having an internal power source and a secondary coil operatively coupled to said internal power source, said implantable medical device adapted to be implanted in a patient; and 
 an external power source having a primary coil, said external power source providing energy to said implantable medical device when said primary coil of said external power source is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current, having a value, passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said current passing through said internal power source comprises a maximum amount of current for charging said internal power source; 
 wherein said current passing through said internal power source declines over time as an internal impedance of said internal power source increases. 
 
     
     
       4. A system for transcutaneous energy transfer, comprising:
 an implantable medical device having componentry for providing a therapeutic output, said implantable medical device having an internal power source and a secondary coil operatively coupled to said internal power source, said implantable medical device adapted to be implanted in a patient; and 
 an external power source having a primary coil, said external power source providing energy to said implantable medical device when said primary coil of said external power source is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current, having a value, passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said external power source terminates its power output if said current passing through said internal power source is below a minimum amount. 
 
     
     
       5. An external power source for use with an implantable medical device adapted to be implanted in a patient and having componentry for providing a therapeutic output, an internal power source and a secondary coil operatively coupled to said internal power source, comprising:
 an external power unit; and 
 a primary coil, operatively coupled to said external power unit; 
 said external power unit providing energy to said implantable medical device when said primary coil is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current having a value passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a measured current associated with said current passing through said internal power source. 
 
     
     
       6. An external power source for use with an implantable medical device adapted to be implanted in a patient and having componentry for providing a therapeutic output, an internal power source and a secondary coil operatively coupled to said internal power source, comprising:
 an external power unit; and 
 a primary coil, operatively coupled to said external power unit; 
 said external power unit providing energy to said implantable medical device when said primary coil is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current having a value passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said current passing through said internal power source declines as said voltage of said internal power source increases during a charging cycle. 
 
     
     
       7. An external power source for use with an implantable medical device adapted to be implanted in a patient and having componentry for providing a therapeutic output, an internal power source and a secondary coil operatively coupled to said internal power source, comprising:
 an external power unit; and 
 a primary coil, operatively coupled to said external power unit; 
 said external power unit providing energy to said implantable medical device when said primary coil is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current having a value passing through said internal power source; 
 wherein said current passing through said internal power source comprises a maximum amount of current for charging said internal power source; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source 
 wherein said current passing through said internal power source declines over time as an internal impedance of said internal power source increases. 
 
     
     
       8. An external power source for use with an implantable medical device adapted to be implanted in a patient and having componentry for providing a therapeutic output, an internal power source and a secondary coil operatively coupled to said internal power source, comprising:
 an external power unit; and 
 a primary coil, operatively coupled to said external power unit; 
 said external power unit providing energy to said implantable medical device when said primary coil is placed in proximity of said secondary coil of said implantable medical device and thereby generating a current having a value passing through said internal power source; 
 wherein said external power source automatically varies its power output based on a value associated with said current passing through said internal power source; 
 wherein said external power source terminates its power output if said current passing through said internal power source is below a minimum amount. 
 
     
     
       9. A method of transcutaneous energy transfer between an external primary coil and an inductively coupled secondary coil of an implanted medical device, said external primary coil being operatively coupled to a charging unit, said secondary coil supplying power to an internal power source of said implanted medical device, said internal power source having an internal impedance, comprising the steps of:
 driving said external primary coil with a charging signal from said charging unit generating a current passing through said internal power source; and 
 said charging unit automatically varying its power output based on a value associated with said current passing through said internal power source; 
 wherein said automatically varying step automatically varies its power output based on a measured current associated with said current passing through said internal power source. 
 
     
     
       10. A method of transcutaneous energy transfer between an external primary coil and an inductively coupled secondary coil of an implanted medical device, said external primary coil being operatively coupled to a charging unit, said secondary coil supplying power to an internal power source of said implanted medical device, said internal power source having an internal impedance, comprising the steps of:
 driving said external primary coil with a charging signal from said charging unit generating a current passing through said internal power source; and 
 said charging unit automatically varying its power output based on a value associated with said current passing through said internal power source; 
 wherein said current passing through said internal power source declines as said voltage of said internal power source increases during a charging cycle. 
 
     
     
       11. A method of transcutaneous energy transfer between an external primary coil and an inductively coupled secondary coil of an implanted medical device, said external primary coil being operatively coupled to a charging unit, said secondary coil supplying power to an internal power source of said implanted medical device, said internal power source having an internal impedance, comprising the steps of:
 driving said external primary coil with a charging signal from said charging unit generating a current passing through said internal power source; and 
 said charging unit automatically varying its power output based on a value associated with said current passing through said internal power source; 
 wherein said current passing through said internal power source comprises a maximum amount of current for charging said internal power source; 
 wherein said current passing through said internal power source declines over time as an internal impedance of said internal power source increases. 
 
     
     
       12. A method of transcutaneous energy transfer between an external primary coil and an inductively coupled secondary coil of an implanted medical device, said external primary coil being operatively coupled to a charging unit, said secondary coil supplying power to an internal power source of said implanted medical device said internal power source having an internal impedance, comprising the steps of:
 driving said external primary coil with a charging signal from said charging unit generating a current passing through said internal power source; and 
 said charging unit automatically varying its power output based on a value associated with said current passing through said internal power source; 
 wherein said external power source terminates its power output if said current passing through said internal power source is below a minimum amount.